Chiral ketones and aldehydes are very important products or intermediates for the synthesis of compounds in the fields of flavours and fragrances or pharmaceutical products and vitamins.
These products have stereogenic centres which makes their properties very unique.
One possibility of creating stereogenic carbon centres is addition of compounds, particularly of molecular hydrogen, to prochiral carbon-carbon double bonds of suitable starting materials.
Classic chemical reactions mainly result in mixtures of the stereoisomers at said stereogenic centres and require the use of expensive separation processes.
Therefore for a long time there has been a large demand for highly stereoselective reactions leading to specific stereogenic configurations.
WO 2006/066863 A1 discloses an asymmetric hydrogenation of alkenes to yield specific configurations of the stereogenic centres being formed by the hydrogenation.
However, technically alkenes very often are mixtures of E and Z isomers.
It is known that carbon-carbon double bonds of alkenes can be isomerized. Transition metal derivatives as well as sulphur compounds such as sulfides or disulfides or monomercaptanes are known to isomerize farnesol as described for example in DE 25 57 837.
U.S. Pat. No. 4,028,385 discloses transition metal catalysts as well as organic sulphur compounds such as sulfides or disulfides or monomercaptanes for the isomerization isomerize of farnesylacetic acids and esters as well as rectification of the corresponding stereoisomeric mixtures.
However, the disclosure of isomerization in these documents has not been in the context of asymmetric hydrogenations.